Draft regulator



March 4 1947- J. w. MILLER DRAFT REGULATOR Filed June 30, 1944 FIG. 4

INVENTOR.

JOHN W. MILLER ATTORNEY Patented Mar. 4, 1947 DRAFT REGULATOR John W.Miller, Lansing, Mich, assignor to Motor Wheel Corporation, Lansing,Mich., a corporation of Michigan Application June 30, 1944, Serial No.542,875

14 Claims. 1

This invention relates to automatic draft regulators for combustionapparatus.

The invention constitutes an improvement in draft regulators of the typeshown in Letters Patent to Don Jones No. 2,079,804 granted May 11, 1937,and No. 2,176,217 granted October 17, 1939, and in Letters Patent No.2,194,608 granted to John W. Miller on March 26, 1940.

The principal object of the present invention. is to provide a draftregulator which is of more simple and economical construction thanprevious regulators.

Another object is to provide a. novel adjusting mechanism for thecontrol weights on such regulators.

A still further object is to provide novel means for attaching thecontrol weight to the draft regulator blade.

These objects will more fully appear in the following specification whenread in connection with the accompanying drawings, wherein:

Figure 1 is a fragmentary front elevational view of a draft regulatorembodying the invention;

Figure 2 is a cross-sectional view taken on substantially the line 2-2of Figure 1;

Figure 3 is a fragmentary cross-sectional view taken on substantiallythe line 3-3 of Figure l (with knob 24 shown in dotted line position ofFigure 1);

Figure 4 is an oblique projectional view of the cam sleeve: and

Figure 5 is a fragmentary cross-sectional view taken on substantiallythe line 55 of Figure 1.

The drawings illustrate an automatic draft regulator comprising a damperblade l0 pivotally mounted on a pivot II in a collar or frame [2. Thecollar 12 is held in the open end of a pipe 13 attached to the flueoutlet of a combustion chamber (not shown). The pivot II is located asubstantial distance above the center of the blade so that a differencein air pressure between that in the flue outlet and the outsideatmosphere, caused by the draft in the flue outlet, tends to swing thelower part of the damper inward and the upper part outward, therebyadmitting air to r the flue. The resistance to such swinging movementcan be regulated by a control unit, indicated by numeral It, mounted onthe damper blade as will more fully appear presently.

The damper blade II] is a sheet metal stamping of circular shapeprovided with integral ribs IE to stiffen the same. It is also providedwith an indentation or pocket 16. the purpose of which will appearpresently. Some distance above the center of the blade are oppositelypressed integral straps to receive the pivot shaft H. The ends of theshaft it are received in suitable bearings 11 in the collar I2 to permitthe blade to pivot.

In the center of the indentation I6 is a circular opening I8 to receivethe control unit I4. Ad-

jacent the perimeter of the indentation It the metal thereof is struckout to form a. plurality of tongues l9 (see Figures 1 and 5), as well asto provide slots 20, the purpose of which will appear hereinafter.

The control unit comprises a sleeve 2|, a shaft 22, a weight 23, and acontrol knob 24 attached to the blade with the sleeve located in theopening 18, The shaft, knob and weight are rotatable and axially movablerelative to the sleeve to shift the center of gravity thereof relativeto the plane of the blade.

The sleeve 2| (see Figures 3 and 4 particularly) comprises a cylindricalbody portion 25 having an axially extending bore 26 therethrough forminga bearing for shaft 22. Opposite axial extremities of the body portion25 are shaped as helical cam surfaces 2'! and 28 arranged in parallelrelation to each other.

A radial flange 29 is located intermediate the ends of the sleeve. Itsouter surface is marked with numerals 1 to 9, each numeral indicating adifferent position of the control shaft and weight relative to thedamper blade. On the back surface of the flange 29 are lugs 30corresponding in number and location to the slots 20 in the blade 10.The lugs 30 are received in the slots to prevent relative motion of thesleeve and blade. The tongues 19, when bent down from the dotted linepositions of Figure 5 to the full line positions, hold the flange 29 onthe blade.

The weight 23 may be made of any suitable heavy material. It has arecess 3| in its end adjacent the blade Ill deep enough to receive thepart of the sleeve 2| extending through the blade, so that the weightmay be moved into juxt p s tion with the blade. A pin 32 extends througha side wall of the recess adjacent its open end into the shaft 22 tohold the weight on the shaft. The pin 32 contacts the cam surface 21 andacts as a cam follower, as will become apparent presently.

The knob 24 on the other end of the shaft 22 can be of any shape, butpreferably it is shaped like a pointer (see Figure 1) so that it willcooperate with the numerals on the flange 29 to indicate setting of theshaft. The knob is fixedly attached in any suitable manner to the shaft22. A deep recess 33 is formed in the knob 24 parallel to the shaft 22.In the recess is a pin 35 and a spring 34. The spring 34 tendsconstantly to separate the pin 35 and knob 24 and as the pin contactsthe cam surface 28, the shaft 22 and weight 23 are pulled outwardly sothat the cam follower 32 is always in engagement with the cam surface21.

From the foregoing it will be evident that as the knob 24 is rotated,the weight 23 is moved toward or away from the plane of the blade. Whenthe weight is farthest from the blade it oifers its greatest resistanceto tilting of the blade about its pivot, and a considerable differencein pressure between the interior and exterior of the flue outlet isrequired to swing the blade to its open position, and thus a relativelyhigh draft can be maintained in the flue. On the other hand, when theweight is nearest the blade it offers little or no resistance to pivotalmovement of the blade, and the draft in the fine is appreciably lowered.The weight can move into the indentation l6 and thus bring the center ofgravity of the entire control unit into the plane of the blade, ifdesired.

The particular construction of the control unit permits of economicalfabrication. The weight and sleeve can be unmachined die castings, whilethe knob can be molded plastic, if desired. No-

machining of threads or slots is required.

Also, the cam arrangement is such that the control unit will not becomeinoperative, or difiicult to operate, because of carbon depositsthereon. Such deposits have affected previous constructions. Nolubrication is necessary.

The scope of the invention is indicated in the appended claims.

I claim:

1. A draft regulator comprising a damper blade pivotally mounted in aframe, and means for varying the resistance of the damper blade topivotal movement comprising a sleeve positioned in spaced relation tothe pivot axis and extending through the blade at an angle to the planethereof, one axial extremity of said sleeve having a substantiallyhelical cam surface, a shaft mounted in said sleeve for longitudinal androtary movement relative thereto, a cam follower fixedly attached tosaid shaft and engaging said cam surface whereby rotation of said shaftcauses movement of the shaft axially of said sleeve, and spring biasedmeans attached to said shaft and engaging the opposite axial extremityof said sleeve to maintain Contact between said cam follower and saidcam surface.

2. A draft regulator comprising a damper blade pivotally mounted in aframe, and means for varying the resistance of the damper blade topivotal movement comprising a sleeve positioned in spaced relation tothe pivot and extending through the blade at an angle to the planethereof, one axial extremity of said sleeve having a cam surface, ashaft mounted in said sleeve for longitudinal and rotary movementrelative thereto, a weight attached to said shaft adjacent said camsurface, a knob attached to said shaft adjacent the opposite end of saidsleeve,

a cam follower rigidly attached to said shaft and engaging said camsurface, and spring biasrd means attached to said knob and engaging theopposite axial extremity of said sleeve whereby rotation of said shaltcauses axial movement thereof relative to said sleeve.

3. A draft regulator comprising a damper blade pivotally mounted in aframe, and means for varying the resistance of the damper blade topivotal movement comprising a sleeve positioned in spaced relation tosaid pivot and extending through the damper blade at an angle to theplane thereof, opposite axial extremities of said sleeve having parallelcam surfaces, a shaft rotatably mounted in said sleeve for rotary andlongitudinal movement relative thereto, and means attached to said shaftadjacent opposite extremities thereof engaging said cam surfaces,whereby rotation of said shaft causes axial movement of said shaft and ashifting of the center of gravity of said shaft relative to the plane ofthe blade.

4. A damper regulator comprising a damper blade pivotally mounted in aframe, and means for varying the resistance of the damper blade topivotal movement comprising a sleeve positioned in spaced relation tothe pivot and extending through said blade at an angle to the planethereof, opposite axial extremities of said sleeve having parallel camsurfaces, a shaft extending through said sleeve for rotatable andlongitudinal movement relative thereto, a weight-attached to one end ofsaid shaft, an actuating knob attached to the other end of said shaft,and means on said weight and said knob engaging the adjacent camsurfaces on said sleeve whereby rotation of said knob causes axialmovement of said shaft, weight and knob relative to said blade.

5. A draft regulator as defined in claim 4 wherein said weight isprovided with an axially extending recess adapted to receive a portionof said sleeve in one position of said weight, and the means on theweight engaging the adjacent cam surface consists of a pin extendingthrough a wall of said recess and fixed to said shaft.

6. A draft regulator as defined in claim 4 wherein the means on the knobengaging the adjacent cam surface comprises an axially movable pinseated in a recess in said knob and a spring in said recess biasing saidpin toward said sleeve.

7. A draft regulator for combustion apparatus comprising a damper bladepivotally mounted in a frame on a pivot substantially in the plane ofthe damper blade, and means for varying the resistance of the damperblade to pivotal movement comprising a sleeve positioned in spacedrelation to the pivot and extending through said blade at an angle tothe plane thereof, opposite axial extremities of said sleeve havingparallel cam surfaces, a shaft extending through said sleeve androtatable therein, a weight attached to one end of said shaft, saidweight having a recess therein adapted to receive one end of said sleevein one position of said weight, a pin extend ing through a wall of saidrecess and fixed to said shaft, said pin engaging the adjacent camsurface on said sleeve. a knob on the other end of said shaft. a pinmounted in a recess in said knob and movable axially thereof. and aspring in said last named recess for biasing said pin toward theadjacent extremity of said sleeve.

8. A draft regulator for combustion apparatus comprising a damper bladepivotally mounted in a frame on a pivot substantially in the plane ofthe damper blade. and means for varying the resistance of the damperblade to pivotal move ment comprising a sleeve in spaced relation to thepivot and extending through the blade at an angle to the plane thereof,said sleeve having a radial fiance thereon intermediate its endsjuxtaposed to said blade, a plurality of recesses in said blade. :1plurality of lugs on said flange s ated in said recesses, and a tonguestruck from said blade and engaging the surface of the flange remotefrom the blade for holding the flange in said juxtaposed relation to theblade.

9. In a draft regulator, the combination with a damper blade 0i counterbalancing means for the same comprising a shaft extending through theblade at an angle to the plane thereof, said shaft being so, ported bythe blade for rotatable and longitudinal movement relative to the blade,a cam supported by the blade and disposed in concentric relation to theshaft on one side of th blade, said cam member having a substantiallyhelical cam surface, a cam follower supported by the shaft for rotationtherewith and adapted to engage said cam surface, and spring In hecarried by the shaft on the opposite side of the blade from the camfollower for biasing the shaft longitudinally to hold the cam followeragainst the cam surface.

10. The combination defined in claim 9 wherein said cam follower iscarried by a counterbalanc- L. weight secured to the shaft.

11. The combination defined in claim 9 wherein said spring means iscarried by an operating knob secured to the shaft.

l2. The combination defined in claim 9 wherein a second cam member issupported by the blade on the side thereof adjacent the spring means andthe spring means cooperates with said second cam member for holding thecam follower against the said first mentioned cam member.

13. In a draft regulator, the combination with a damper blade ofcounterbalancing means for the same comprising a shaft extending throughthe blade at an angle to the plane thereof, said shaft being supportedby the blade for longitudinal and rotatable movement relative thereto, acam member supported by the blade in concentric relation to the shaft onone side of the blade, said cam member having a substantially helicalcam surface, cam follower carried by the shaft and adapted to engagesaid cam surface, and spring biased means carried by the shaft on theopposite side of the blade from the cam follower, said spring biasedmeans being arranged to act against a contact member carried by theblade to hold the cam follower against the cam surface.

14. The combination defined in claim 13 wherein said contact member is acam and the spring biased means includes a cam follower resilientlypressed against said cam.

JOHN W. MILLER.

Name Date Bock May 30, 1933 Number

